Where can Class C fly ash be found for making bricks?
In the United States, approximated 50% of the fly ash is Class C. The Class C ash is generated by burning Western coals, usually subbituminous or lignite. For instance, the largest coal source and reserve in the United States Powder River Basin Coals produces Class C fly ash. For bituminous coals produced in Eastern states, they normally produce Class F fly ash. However, if such coals are burned with limestone in fluidized boilers in order to remove the sulfur from the coals, or if powdered limestone is injected into the exhaust flue gas using a clean coal technology called flue gas desulfurization (FGD), the fly ash produced from such a system, regardless of the type of coal used, will contain high amount of calcium oxide (CaO). Therefore, there is plenty of high-calcium fly ash in the United States for making fly ash bricks, more so in the Western states than Eastern states.
